Starting device for electric motors



(No Model.)

B. P. SHARP STARTING DEVICE FOR ELECTRIC MOTORS. No. 445,907. PatentedFeb. 3, 1891.

WITNESSES. F1641 INVENTOH.

46M Ta U NITED STATES PATENT OFFICE.

EDWUXRD PEARCE SHARP, OF BOSTON, MASSACHUSETTS.

STARTING DEVICE FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 445,907, dated February3, 1891.

Application filed March 18, 1890.

To all whom it may concern:

Be it known that I, EDWARD PEARCE SHARP, of the city of Boston, countyof Sulfolk, and State of Massachusetts, have invented certain new anduseful Improvements in Automatic Rhcostats or Safety-Starters forElectric Motors, of which the following is a full and exact description,reference being had to the accompanying drawings, which form a part ofthis specification, and to the letters of reference marked thereon.

In the drawings, Figure 1 is an elevation comprising a generalillustration of my improvements and their connections and relation tothe motor. Fig. 2is a side elevation of electro-magnet 6, its armature'2', latch 7:, to. Fig. 3 is a corresponding endelevation. Fig. 4 is aside view in elevation of electromagnet (I. Fig. 5 is a correspondingend elevation. Fig. 6 is a side elevation illustrating the contact ofarm f with the contact-plates g by means of its brushes m. Similar viewsare Figs. 7 and S, the construction therein being slightly varied in thematter of the brushes. Fig. 9 illustrates the winding up of the spring sby the movement of lever F in operating the switch. This is a substituteswitch.

Like letters refer to the same or corresponding parts in all thefigures.

The nature of my invention relates to the mechanism devised forcontrolling and graduating the amount of electrical current passing tothe motor and indicating promptly an y inefliciency or failure of saidcontrol or graduating of the amount of electrical current, whetherarising from accidental or other causes.

The invention consists in the employment of a rotary mechanism combinedwith a series of resistance-coils and contact-plates, whereby one afteranother of the resistances are cut out from a circuit until, when themotor is fully at work, the circuit becomes direct; also, in theemployment of an electric lamp or other signal placed in or closelyconnected to the circuit, so as to be brought into action by anyabnormal increase of electrical current, together with various devices,arrangements, connections, and combinations hereinafter more fully setforth.

The object, as already apparent, is to prevent or obviate the danger ofinjury to the Serial No. 344,402. (No model.)

motor and various parts and connections by any abnormal or excessivecurrent.

Referring to the drawings, sis a spindle which carries the rheostat-armf. This spindle is supported in any suitable bearings and iselectrically connected to the binding-post t. The contact-plates g arearranged in a circle around spindle s, and each is connected to aresistance-coil r. The arm f is provided with a brush or brushessuitable to insure electrical connection between arm f and eachcontact-plate 9 while the arm f is passing over it in its rotarymovement around the axis of spindle s.

The electro-magnets (Z and c are arranged conveniently for connectingsubstantially as shown, and are provided with suitable pivoted ormovable armatures h and t. These armatu res have springs holding them ordrawing them back out of contact or away from their respective magnetsand against any suitable stop. The armature i is electrically con nectedto post i, and is also held positively away from its magnet by means ofa tilting latch is or equivalent device until the arm f in passing tiltsit and so unlocks or unlatches the armature and leaves it free to beattracted to the magnet c. The armature 7L serves as a stop to arm f,preventing its rotary movement toward the left, as shown, until themagnet (Z becomes active and attracts it to itself, and so releases armf. The resistancecoils are electrically connected from magnet c tomagnet (I, and these, respectively, to binding-posts a and f. Armatureis electrically connected to binding-post Z. An electrical lamp or otherequivalent device susceptible to operation by means of an electriccurrent passing through it is electrically connected to the line leadingto the motor, as seen at binding-post r. This connection passing throughthe lamp is also connected to an armature b in movable relation toelectromagnet a, said armature being pivoted similarly to 7L and 'z' andheld by a spring away from magnet a against a suitable stop 0.Bindingpost to is electrically connected to uand c. Electro-magnet cl isconnected to the line through bindingpost 00; also, as shown, tobinding-post 1 The motor is connected, as shown, to posts i, g and w,and all parts of the mechanism not electrically connected of courseshould be properly insulated with respect to each other.

The springI have shown for operating with a circular movement the arm fby means of gearsis marked A. This spring may be wound up by anarrangement combining it with the swit'ch-lever'F.

For the purpose of illustrating the combination I have shown asubstitute switch in Fig. 9. A glance at this view will make theoperation apparent. WVhen the lever F is moved toward the observer toclose the switch, the pawl E drags over the notches in the wheelconnected with the springs barrel and is held up by pin B. On moving thehandle reversely to open the switch the pawl takes hold, turns thewheel, and winds the spring.

The operation is as follows: The electrical circuit being. completed bythe closing of the switch '0, it passes through magnet e and theresistance-coils r to magnet d, thence through binding-post t and lineto motor, post y, coil a, post 00, and line. Magnet 01 thus becomesactive and attracts armature h to itself, and so unlocks arm f, whichbegins to rotate, passing first to theleft. Coming into contact withplate g, connection is made through g, arm f, and spindle s to post iand the motor, cutting out magnet d and allowing armature h to be drawnback out of contact by its spring. The arm f, still moving on, comes incontact with plate g, by which contact plate 9 and its resistance-coilare cut out of the circuit. Arm f, still passing on around the circle,makes contact with plate g whereby plate g and its resistance-coil arecut out of the circuit, and so on until the arm f, making contact with gg", and g7, so leaves out of the circuit, successively eachresistance-coil and comes in contact with and tilts the latch 75,

- so releasing armature t', Whichimmediately is current passes throughcoil and core of magnet c and armature 2' direct to t, and thence to themotorand the line. In case of any sudden stopping and starting of thecurrent-as, for instance, in case of a break in the circuit on thelinemagnet 6 will cease to be a magnet, and so allow armature i to bedrawn out of contact by its spring, where it will be automatically heldby latch is until again released by arm f, as described. If by anychanceor otherwise the described operation has in any case failed, and anabnormal amount of electrical current is flowing through the motor, themagnet a will become active, and, according to the previous properadjustment of the tension of springs, will draw armature binto contactwith itself, (overcoming the said tension of spring .2.) Thecurrentisthus allowed to flow through armature b to and through the lamp 1 orequivalent electrical signal, so giving suitable notice or alarm,

The parts may be constructed of the materials common to the art orothers suited to the described conditions and operations.

Any suitable power, as a spring or weight with suitable wheels andregulating device, may be used to rotate the arm f. I have shown aspring and ordinary clock-work.

I claim- 1. In a rheostat or starter for electric motors, thecombination of magnet (Z in the line, its armature-releasing latch andstop h, the automatically-rotatory contact-arm carrying brushes, acircular series of contact-plates over which said brushes move withresistancecoils connected to said plates, the line-magnet 6, itscircuit-closing armature 1', and latch 7c, operated by said contact-armto release said armature i, so closing the short circuit, substantiallyas described.

7 2. The combination of the line-magnet (Z,

its releasing-armature 71, the automaticallyrotatory contact-arm, itsbrushes, contactplates, and resistances, line short-circuiting magnetand armature e 2', and latch 7c, operated by said contact-arm,substantially as described. i

3. The combination of the latch 75, armature i, magnet e in the line,the automatically-re. tatory contact-arm, and its series of contact--plates and resistances for the purpose of shortcircuiting the currentwhen the resistances are cut out, substantially as described.

4. The combination of the magnet din the line, its armature latch-andstop h for releas-.

ing and stopping the contact-arm, the automatically-rotatorycontact-arm, its contactplates, plate contact -brushes, resistances, andthe circuit-closing armature 'L', line-magnet e, and armature-releasinglatch 7c, operated to close the short circuit by the contactarm,substantially as described.

5. The double-function hand-lever F, provided with contact-plate '0' andpawl E, in combination with the'contact binding-posts for connection toline and rheostat and the winding ratchet-wheel on the barrel or shaftgiving motion to the rotatory contact-arm, substantially as described.

6. In a rheostat or starter for electric mo: tors, the combination of anautomatically-rotatory contact-arm, a retaining armaturelatch h, areleasing line-magnet (Z, a circular series of contacts and connectedresistances,

a short-circuiting latch-holder armature i, and'magnet c in the line,substantiallyas de-v Witnesses:

F. M. IIooPER, D. N. B. COFFIN.

IIO

